Investing apparatus

ABSTRACT

Investing apparatus including a vacuum chamber in which flasks are filled with refractory slurry, a mixing kettle adapted to be charged with the materials required to make the slurry, and equipment for measuring out and charging into the kettle predetermined amounts of the slurry materials. A system for automatically controlling the operations of the apparatus is provided.

United States Patent [1 1 Erndt INVESTING APPARATUS [75] Inventor: Edmund E. Erndt, Timberlake,

Ohio

[73] Assignee: Precision Metalsmiths, Inc., Cleveland, Ohio [22] Filed: July 9, 1970 [21] Appl. No.: 53,503

[52] U.S. Cl. ..14l/5l,l4l/67, 141/107, 141/231, 177/116, 259/154 [51] Int. Cl. ..B6Sb 31/02 [58]v Field of Search ..l4l/51,67, 107, 83,231; 177/116, 89, 120; 259/8, 154; 302/21;

[5 6] References Cited UNITED STATES PATENTS 2,720,375 10/1955 Carter ..l77/l66 X ELECTRIC MAIN CONTROL PANEL 35 152 p 0 0 0? 0 1 March 6, 1973 Eirich et al. ..259/l54 X 2,884,963 5/1959 Emdt ..141/5l 2,946,574 7/ 1960 Munderich i ..259/ 154 X 3,168,926 2/1965 Dietert .,.l77/1l6 X 3,236,565 2/1966 Kester et a1 ..302l2l X Primary Examiner-Houston S. Bell, Jr. Attorney-Watts, Hoffman, Fisher and Heinke [5 7 ABSTRACT Investing apparatus including a vacuum chamber in which flasks are filled with refractory slurry, a mixing kettle adapted to be charged with the materials required to make the slurry, and equipment for measuring out and charging into the kettle predetermined amounts of the slurry materials. A system for automatically controlling the operations of the apparatus is provided.

4 Claims, 2 Drawing Figures INVESTING APPARATUS BACKGROUND OF THE INVENTION The present invention relates generally to the art of investment casting, and more specifically to apparatus for making investment molds.

The steps involved in investment casting include making an expendable pattern which has the configuration of the desired metal casting. This pattern, which may be made of wax, plastic or other expendable material, is commonly referred to as a set-up or tree. The set-up or tree is placed within a flask and is surrounded with a refractory slurry which is allowed to harden in the flask to produce the investment mold. In subsequent operations, the set-up or tree is removed from the mold, as by heating the mold to an elevated The refractory powder, binder and water are mixed together to form a slurry which is then introduced into the flasks around the set-ups or trees as described above and allowed to set or harden. In some instances, an anti-forming agent is added to the slurry to suppress foaming during the mixingoperation. It is preferred to mix the slurry and to fill the flasks under a vacuum. In this way air and other gases are prevented from being trapped in the slurry to form bubbles which result in rough mold surfaces.

Apparatus for mixing refractory slurry and introducing it into flasks to make investment molds is known and is disclosed in US. Pat. No. 2,884,963, issued May 5, 1959 to Edmund E. Erndt. This prior art apparatus is comprised of a mixing kettle which can beevacuated during the mixing operation, a vacuum chamber in which flasks are filled with the slurry, and a valved conduit between the outlet of the kettle and a filling spout within the vacuum chamber. The operation of this prior art apparatus requires constant attention by two skilled operators in order to produce satisfactory molds. The operator is required to weigh out the necessary amounts of refractory material and binder and to place these materials into the mixing kettle together with the exact amount of water necessary to make the slurry. The functions of the prior art apparatus, including the mixing time and the time period during which the flasks are filled with slurry, are manually controlled by the operator. 1

SUMMARY OF THE INVENTION An object of the present invention is to provide an investing apparatus of the type described with equipment for automatically measuring out and charging into a mixing kettle predetermined amounts of the materials required to make an investment slurry.

Another object of the present invention is to provide an investing apparatus of the type described with equipment for automatically weighing out the required amount of refractory powder necessary to make an investment slurry.

A further object of the present invention is to provide an investing apparatus of the type described with equipment for automatically weighing out the amount of refractory powder necessary to make an investment slurry and for charging the powder into the mixing kettle of the apparatus.

Still another object of the present invention is to provide an investing apparatus of the type described with a system for introducing into the mixing kettle the required volume of liquid and any desired additives necessary to make an investment slurry.

A more specific object of the present invention is to provide an investing apparatus including a vacuum chamber in which flasks are filled with refractory slurry, a mixing kettle which is connected to a filling spout in the vacuum chamber and which is adapted to be evacuated during mixing of the slurry, equipment for automatically weighing out the required amount of refractory powder, a system for transferring the weighed refractory powder to the mixing kettle, and a system for introducing into the mixing kettle the required volumes of liquid and any special additive necessary to make the slurry.

Still another object of the present invention is to provide an investing apparatus as described in any of the preceding paragraphs and including a system for automatically controlling the operation of the apparatus.

Other objects and advantages and a fuller understanding of the invention will be had by reference to the accompanying drawings and the following detailed description;

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a view diagrammatically illustrating the preferred embodiment of the invention, including the control system for effecting automatic operation of the apparatus; and

FIG. 2 is a schematic elevational view of the weighing equipment which comprises one aspect of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The investing apparatus of this invention is comprised of equipment for automatically weighing out a predetermined amount of refractory powder to be used in preparing a refractory slurry, a mixing kettle in which the powder is mixed with water and any desired additives, a vacuum transfer system for transferring the refractory powder to the kettle, a metering system for introducing into the kettle measured volumes of temperature controlled water and special additive, and a vacuum chamber in which flasks are filled with the refractory slurry to make investment molds. FIG. 1 diagrammatically illustrates the preferred arrangement of the apparatus, including the vacuum transfer conduit, ducts for compressed air and water, the vacuum lines and the electrical control system. The electrical conduits of the control system are represented in FIG. 1 by heavy lines and will be understood to contain one or more circuits which are electrically connected to the various valves, switches, and control boxes in a manner which will be readily apparent to those skilled in the art in view of the following description.

Referring to the drawings, the automatic weighing equipment for the refractory powder includes a scale 10 on which is mounted a weigh hopper 11. Vibrators 12 are attached to the weigh hopper 11 to prevent packing of refractory powder in the hopper. The scale includes a control unit 13 having an adjustable pointer 14 which can be set to the desired weight of refractory powder.

Refractory powder which preferably includes a binder is fed into the weigh hopper 11 from either of two feed hoppers 15, 16 mounted above the weigh hopper. The feed hoppers 15, 16 are provided with slide gates 17, 18, respectively, which are movable to open and close the bottoms of the feed hoppers. The slide gate 17 is operated by an air cylinder unit 19. A two-way valve 20 controlled by solenoid-operated pilot valves 21, 22 is provided for admitting air under pressure to the cylinder unit 19. Compressed air is supplied to the valve 20 through an air line 23 which is connected to a main compressed air line 24. The valve 20 is connected to one end of the cylinder unit 19 by an air line 25 and to the other end of the cylinder unit by an air line 26. The slide gate 18 is operated in the same manner as the gate 17 by an air cylinder unit 29 and an associated two-way valve 30 controlled by solenoidoperated pilot valves 31, 32. The valve 30 is connected to the cylinder unit 29 by air lines 35, 36 and to the main compressed air line 24 by an air line 33.

The feed hoppers 15, 16 also include motor driven feed screws 40, 41, respectively, which extend through the feed hoppers above the slide gates. The feed screws I are actuated when the slide gates are opened to feed the powder into the weigh hopper 11. Electrical vibrators 42 are attached to the outsides of the feed hoppers 15, 16. The vibrators 42 prevent bridging of the refractory powder in the openings of the hoppers during the feeding operation.

Portable bins 45, 46 are supported above the feed hoppers 15, 16 respectively. Motor driven feed screws 47, 48 similar to the feed screws 40, 41 extend through the portable bins 45, 46. The bins also include electrical vibrators 49. It will be understood that the bins 45, 46 are selectively emptied into the feed hoppers and are then replaced. Preferably, each of the feed hoppers 15, 16, is of a size to hold an uninterrupted supply of refractory material when the portable bin above the feed hopper is being replaced.

The scale control unit 13, the solenoids for operating the gate actuating valves 20, 30, the motor driven feed screws 40, 41, 47, 48, and the vibrators 42, 49 are electrically connected to a weighing and feeding control panel 50. A selector switch 51 on the control panel is in circuit relation with a start switch 53, the solenoids 21, 22 of the valve 20, the motor driven feed screw 40 and vibrator 42 of the feed hopper 15, and the motor driven feed screw 47 and vibrator 49 of the portable bin 45. A second selector switch 52 is in circuit relation with the start switch 53, the solenoids 31, 32 of the valve 30, the motor driven feed screw 41 and vibrator 42 of the hopper 16, and the motor driven feed screw 48 and vibrator 49 of the portable bin 46.

The feeding and weighing operations are commenced by setting the pointer 14 of the scale control unit 13 to the desired weight of refractory powder and actuating the desired selector switch 51 or 52 and the start switch 53. Assuming that the selector switch 51 has been activated, the valve 20 is operated to admit compressed air to the cylinder unit 19 so as to open the slide gate 17. At the same time, the feed screw 40 and the vibrator 42 of the hopper 15 are activated together with the feed screw 47 and the vibrator 49 of the portable bin 45 Refractory powder from the portable bin 45 is fed into the feed hopper 15 and then into the scale hopper 11. When the scale hopper 11 has been filled with the amount of refractory material determined by the setting of the pointer 14, the valve 20 is operated to reverse the flow of compressed air to the cylinder unit 19 and thereby close the slide gate 17 Concurrent with the closing of the slide gate 17, the feed screw and vibrator 42 of the feed hopper 15 and the feed screw 47 and vibrator 49 of the bin are stopped. Refractory material may be fed into the scale hopper 11 from the portable bin 46 and the feed hopper 16 by a similar sequence of operations when the selector switch 52 is activated.

As described above, the sequence of feeding and weighing operations and the actuation of the feed screws, vibrators, etc. are carried out automatically by activating the desired selector switch 51 or 52 and the start switch 53. if desired, the operator can override any of the operations by actuating individual selector switches on the panel 50. The control panel is shown in FIG. 1 as including a switch 54 for operating the gate actuating valves 20, 30 and the feed hopper screws 40, 41, a switch 55 for operating the feed hopper vibrators 42, a switch 56 for operating the portable bin feed screws 47, 48, and a switch 57 for operating the portable bin vibrators 49.

The refractory slurry is prepared in a kettle by mixing dry refractory powder with liquid, such as water, and any desired additives. As shown, the kettle 65 includes an agitator 66 which is driven by a motor 67. The motor 67 is electrically connected to a mixer switch 68 and a vacuum transfer switch 74 on a main control panel 69.

In the preferred embodiment of the invention, a vacuum transfer system is provided for conveying the weighed powder to the kettle 65. This vacuum transfer system includes a conduit 70 which is connected to the weigh hopper 11. The conduit 70 communicates with a charging port of the kettle 65 through an air actuated, pinch-type valve 71. The pinch-type valve 71 is of conventional construction and includes a flexible sleeve mounted within a casing. By introducing compressed air into the valve casing through a pipe 72, the flexible sleeve of the valve may be constricted to close the valve. The flow of compressed air in the pipe 72 is controlled by a solenoid-operated valve 73. The valve 73 is electrically connected to the vacuum transfer switch 74 on the main control panel 69.

The vacuum transfer system for conveying the refractory powder to the kettle 65 also includes a vacuum source and filter unit 75. The vacuum source and filter unit 75 is connected to a dust separator 76 by a vacuum line 77, and the separator 76 is in turn connected to the top of the kettle 65 by line 78. During operation of the apparatus, damp refractory powder may be carried out of the kettle 65 into the vacuum lines connected to the kettle. The purpose of the separator 76 is to trap the damp powder and thereby prevent accumulations of hardened investment material from plugging the vacuum lines. As diagrammatically shown in FIG. 1, the separator 76 includes suitably arranged baffle plates 79. 1

A pinch valve 80 which is similar to the previously described pinch valve 71 is provided in the vacuum line 77 between the vacuum source 75 and the separator 76. Compressed air for actuating the valve 80 is sup plied to the valve casing through a connected pipe 81 and a solenoid operated valve 82 which is mounted in the pipe. The solenoid operated valve 82 and the vacuum source 75 are electrically connected to the vacuum transfer switch 74 of the main control panel.

A vacuum transfer system timer 83 is preferably provided on the control panel 69 in circuit relation with the transfer switch 74. When the switch 74 is pressed, the timer 83 is activated, the valves 71, 80 are opened and the vacuum source 75 is turned on. At the end of the preset period determined by timer 83 all of the powder will have been transferred to the kettle 65. At this time the solenoid valves 73, 82 are actuated to close the valves 71, 80, respectively, and the vacuum unit 75 is turned off.

In order to facilitate the powder transfer operation, the powder is preferably air-fluidized in the weigh hopper 11. As shown, an aerator 84 is connected to the bottom of the hopper 11. Compressed air is supplied to the aerator 84 through a pipe 85 and a solenoidoperated valve 86 in the pipe. The valve 86 and the hopper vibrators 12 are in circuit relation with the switch 74 and the timer 83 so as to be operated when the switch 74 is pressed to start the transfer operation.

The system for automatically supplying a measured volume of water at regulated temperature to the mixing kettle 65 includes a water temperature regulator 90, a water meter 91 formeasuring the amount of water flowing through the temperature regulator, asolenoidoperated control valve 92, and an electrical impulse counter 93 which is in circuit relation with the water meter 91 and the valve 92. The temperature regulator 90 has one of its inlet ports connected to a hot water supply pipe 94 and the other of its inlet ports connected to a cold water supply pipe 95. The regulator 90 mixes the hot and cold water together and can be adjusted to obtain a mix water of the desired temperature. The mix water is supplied to the water meter 91 through a pipe The water meter 91 is activated by the water flowing through it and sends an electrical impulse to the counter 93 for each measured volume of water. By way of example, the meter 91 may transmit an electrical impulse to the counter 93 for each one-half pint of water flowing through the meter. In operation the counter 93 is set to obtain the desired volume of water. When the counter 93 is started by the operator, the solenoid valve 92 is opened to permit the flow of water into the kettle 65. As shown, the valve 92 is mounted in a pipe 97 which is connected to the meter 91 and to a pipe 98 which communicates with the top of the kettle 65. The valve 92 is automatically closed by the counter 93 after the predetermined volume of water has flowed through the meter 91.

A special additive, such as an anti-foaming agent, may be introduced into the mixing kettle 65 together with the water. In the illustrated embodiment of the invention, the additive is supplied from a source 105 which is connected to the pipe 98 by a pipe 106..A normally closed, solenoid-operated valve 107 is mounted in the pipe 106 and is electrically connected to additive selector switch 1 on the main control panel 69. When the selector switch 108 is activated, the valve 107 is opened. An electrically operated metering pump 1 is mounted in the pipe 106 between the source and the valve 107. The pump 109 is electrically connected to the impulse counter 93 so that the pump will inject a pre-set, measured volume of additive for each electrical impulse generated by the water meter 91. With this arrangement, the volume of additive which is pumped into the kettle is controlled in relation to the volume of water passing through the meter 91.

The mixing kettle 65 is adapted to be placed under a vacuum to prevent air and other gases from being trapped in the slurry during the mixing operation. As shown, a vacuum line is connected to the separator 76 and to a suitable vacuum source. An electrically operated selector valve 116 is mounted in the vacuum line 1 15 for selectively communicating the kettle to the vacuum source or to a vent pipe 117. An air-actuated, pinch-type valve 1 18 is connected to the vent pipe 1 17 and is operated by compressed air supplied through a compressed air line 119 and a solenoid-operated valve 121). The valves 116, 120 are electrically connected to a timer 121 and a kettle vacuum switch 122 on the main control panel 69. When the valve 120 is opened, compressed air is admitted to the casing of the valve 1 18 to constrict the flexible sleeve mounted in the casing and thereby close the vent pipe 117. A filter 123 may be provided in the vacuum line 115 between th selector valve 1 16 and the separator 76.

A vacuum chamber in which flasks are filled with refractory slurry to produce investment molds is designated by reference numeral 130. A work tray 131 adapted to support a plurality of flasks (not shown) is slidably mounted within the vacuum chamber above a vibrator 132. The work tray 131 is vibrated to promote a complete and compact filling of the supported flasks with refractory slurry.

Refractory slurry from the mixing kettle 65 is successively introduced into the flasks supported on the work tray 131 through a swingable filling spout 133. The spout 133 is rotatable about a vertical axis so that its discharge end can be selectively located above each of the flasks, as more particularly described in US. Pat. No. 2,884,963. The refractory slurry is supplied to the spout 133 through a pinch valve 134 which is connected to the discharge end of the mixing kettle 65. The pinch valve 134 is actuated by compressed air supplied to the valve casing through a compressed air line 135. A solenoid-operated valve 136 is mounted in the compressed air line and may be operated by a switch 137 on a chamber control panel 138.

The chamber 130 is provided with a vertically movable door 145. The door is actuated between its open and closed position by an air cylinder 146 which has its piston rod 147 connected to the door. A twoway fluid valve 150, which is controlled by solenoidoperated pilot valves 151, 152, is provided for admitting air under pressure to the cylinder 146. Compressed air is supplied to the valve 150 through a conduit 153 which is connected to the main compressed air conduit 24. The valve 150 is connected to one end of the cylinder 146 by a conduit 154 and to the other end of the cylinder by a conduit 155. Operation of the valve 150 may be controlled by a door switch 156 on the panel 138 which is electrically connected to the solenoids 151, 152. The solenoids 151, 152 also are in circuit relation with the cycle timer 121 on the main control panel 69.

Also associated with the door 145 are air cylinder clamping units 165 which serve to draw the door against the chamber opening to achieve a vacuum seal when the door is in its lower position. Compressed air is supplied to the cylinder units 165 through a two-way flow valve 166, the operation of which is controlled by solenoid-operated pilot valves 167, 168. The valve 166 is connected to the main air line 24 by a branch line 169 and to each of the cylinder units 165 by lines 170 and 171. A limit switch 175 is mounted on the chamber 130 and is electrically connected to the solenoidoperated pilot valve 167, 168. The limit switch 175 is contacted by a stop on the door 145 when it is moved to its lowered position to actuate the cylinder units 165 and effect the door clamping operation.

A vacuum line 176 is connected to the chamber 130 and to a suitable vacuum source for the purpose of placing the chamber 130 under a vacuum when the flasks are being filled with slurry. An electricallyoperated selector valve 177 which is selectively operable to communicate the chamber 130 to the vacuum source or to a vent pipe 178 is mounted in the vacuum line 176. An air-actuated pinch valve 179 is connected to the vent pipe 178 and is operated by compressed air supplied through a compressed air line 180. A solenoid-operated valve 181 is provided in the air line 180 for controlling operation of the valve 179. The valves 177, 181 are electrically connected to the limit switch 175 so that the valve 177 is operated to connect the chamber 130 to the vacuum source and so that the valve 181 is operated to close the valve 179 and the vent pipe 178 when the chamber door 145 reaches its lowered position. The valves 177, 181 also are in circuit relation with the timer 121 and a chamber vacuum override switch 182 on the main control panel 69. As shown, a vacuum filter 183 is provided in the line 176.

At the end of the investing operation and after the door 145 has been raised to open the chamber 130, the work tray 1 1 on which the invested flasks are supported is ejected from the chamber by actuation of an air cylinder 185. The air cylinder unit 185 is connected to the back of the chamber 130 and has its piston rod extending into the chamber in abutment with the tray 131. Air under pressure is supplied to the cylinder unit 185 through air lines 186 connected to a two-way flow valve 187. The valve 187 is connected to the main compressed air line 24 by an air line 188. Operation of the valve 187 is controlled by solenoid-operated pilot valves 189. The solenoid-operated pilot valves 189 are electrically connected to a limit switch 190 which is mounted in association with the chamber 130 so as to be contacted when the door 145 is moved to its up posi tion. When the door 145 is opened to trip the limit switch 190, the valve 187 actuates the cylinder unit 185 to eject the work tray 131 from the chamber. The pilot valves 189 also are in circuit relation with an override switch 191 on the control panel 138.

The preferred embodiment of the invention includes provisions for washing out the mixing kettle 65, the separator 76, and the vacuum chamber 130 at the end of each investing operation. To this end, a water pipe 192 is connected to the top of the separator 76 and to the top of the kettle 65. The pipe 192 communicates with the water supply pipes 94, 95. The flow of water through the pipe 192 may be controlled by a solenoidoperated valve 193 which is in circuit relation with the timer 121 and a kettle spray override switch 194 on the main control panel 69. A spray head 195 is provided in the vacuum chamber 130 and is connected to a water supply pipe 196. The pipe 196 communicates with the main water supply pipes 94, 95, and the flow of water in the pipe may be controlled by a solenoid-operated valve 197. The valve 197 also is in circuit relation with the timer 121 and a chamber spray override switch 198 on the main control panel 69. If desired, manually operated valve 199, 200 may be provided for controlling the flow of water to the pipes 192, 196.

Provision is also made for supplying a retarder solution to the mixing kettle in emergency situations, such as in the event of a failure of any part of the control system during the mixing operation. The purpose of the emergency retarder solution is to prevent the slurry from hardening in the kettle 65. The retarder solution is supplied from a source 205 which is connected to the pipe 98 by a pipe 206. A solenoidoperated pilot valve 207 is provided in the pipe 206 and is electrically connected to an emergency retarder switch 208 on the control panel 69.

The operation of the apparatus will be largely apparent from the foregoing description. A tray 131 of flasks to be filled with slurry is placed in the chamber and the door switch 156 on the panel 138 is pressed to actuate the door cylinder 146 to move the door to its closed position. When the door reaches its closed position, the limit switch is tripped to actuate the door clamping cylinder units 165. The limit switch 175 also causes the valves 177, 179 to be operated to place the chamber 130 under a vacuum.

The weighing and feeding operations are commenced by setting the scale control unit pointer 14 to the desired weight of powder and then pressing the selector switch 51 or 52 and the start switch 53 on the panel 50. This causes refractory powder to be fed from the selected feed hopper 15 or 16 and the associated supply bin 45 or 46 into the weight hopper 11. When the predetermined amount of powder has been fed into the weigh hopper 11, the feed screws and vibrators of the selector feed hopper and supply bin are automatically stopped and the slide gate of the feed hopper is closed. As described above, the automatic operations of the feeding and weighing equipment can be overridden by actuation of the selector switches 54-57 on the panel 50.

During the time that the feeding and weighing operations are being carried out, the operator adjusts the impulse counter 93 to the desired volume of water and then starts the counter. This opens the valve 92 so that temperature regulated water flows through the meter 91 into the kettle 65. The impulse counter 93 automatically closes the valve 92 after the preset volume of water has passed through the meter 91. If the special additive from the source 105 is required, the operator presses the additive selector switch 108 on the control panel 69. Activation of the switch 108 causes a preset volume of additive to be injected in the kettle 65 by the metering pump 109 for each electrical impulse generated by the water meter 91.

After the weighing operation has been completed, the operator presses the vacuum transfer switch 74. This starts the mixer motor 67 and the vacuum source 75, closes the kettle vent pipe valve 118, and opens the kettle charging port valve 71 and the valve 80 in the vacuum source line 77. Activation of the switch 74 also starts the transfer system timer 83, the weigh hopper vibrators 12, and the weigh hopper aerator 84.

The refractory powder is transferred from the weigh hopper 11 to the kettle 65 during the period set by the timer 83. At the end of the timed powder transfer cycle, the following functions are automatically activated.

The vacuum source 75 is shut off together with the weigh hopper vibrators 12 and the aerator 84. At the same time the valve 118 in the kettle vent pipe 117 is reopened and the valves 71, 80 are closed. The closing of the valves 71, 80 serves to isolate the vacuum transfer system from the kettle vacuum line 115. The timer 83 also activates the timer 121 at the end of the transfer cycle.

The timer 121 controls the mixing cycle, the flask filling cycle, and a kettle and chamber wash-down cycle. Activation of the timer 121 operates the kettle vacuum valve 1 16 to a position by-passing the vent pipe 1 l7 and connecting the kettle 65 to the vacuum source through the line 1 15. The slurry is mixed during a timed period set by the timer 121, and at the end of this period a warning signal (not shown) on the panel 138 is activated to signal the operator that the mixing cycle has been completed. At the same time the work tray vibrator 132 is started.

The operator then presses the switch 137 on the panel 138 to open the valve 134 so that the slurry can enter the chamber 130 through the filling spout 133. The spout 133 is successively positioned by the operator over each flask on the tray 131 to fill it with slurry. In order to assist the flow of slurry from the kettle 65, the kettle is preferably vented to atmosphere. To this end the valve 116 is in circuit relation with the switch 137 so that the valve will be operated to connect the line 1 to the vent pipe 1 17 when the switch 137 is activated. The pressure of the atmosphere on the slurry positively forces it through the opened valve 134.

The door cylinder valve 150 is activated to cause the cylinder 146 to raise the door 145 at the end of a timed cycle set by the timer 121. At the same time, the valves 177, 179 are operated to vent the chamber 130 and the door clamping cylinder units 165 are released. The limit switch 190 is tripped by the door when it reaches its up position to actuate the cylinder unit 185 and eject the tray 131 of filled flasks. The timer 121 also starts a wash down cycle by opening the valves 193, 197. At the end of the timed wash down cycle, all functions of the apparatus are shut down preparatory to another operational cycle.

It will be apparent from the foregoing that the objectives of providing an investing apparatus which is automatically controlled and which is operable to measure out and charge into the mixing kettle predetermined amounts of refractory powder and liquid required to make an investment slurry have been accomplished. All operations of the apparatus from the weighing of the refractory powder and the charging of the powder and liquid to the final ejection of the filled flasks and the wash down of the kettle and vacuum chamber can be carried out with a minimum amount of attention by the operator. The time cycles of the various operations preferably are predetermined and are preset by the timers 83, 121 so as to assure that the slurry is properly prepared and that the flasks are filled with the slurry at the correct time and without undue delay. The preferred embodiment of the invention also includes provisions for overriding any of the timed functions of the apparatus if the need arises.

Many modifications and variations of the invention will be apparent to those skilled in the art in the light of the detailed disclosure. Therefore, it is to be understood that, within the scope of the appended claims, the invention can be practiced otherwise than as specifically shown and described.

What is claimed is:

1. An investment apparatus comprising:

a. a container for use in mixing refractory powder and liquid to make an investment slurry,

b. power actuated mixingmeans in said container,

c. powder supply means including a portable bin and a power driven feed member associated with said bin for assisting in discharging powder therefrom,

d. a feed hopper for receiving powder discharged from said portable bin, said feed hopper having a discharge outlet and gate means selectively actuatable to open and close said outlet,

e. a power driven feed member associated with said feed hopper for feeding powder through said discharge outlet when it has been opened by said gate means,

f. weighing means for weighing out a desired amount of powder, said weighing means including a weigh hopper positioned to receive powder discharged from said feed hopper,

g. control means in electrical circuit relation with said gate means, said power driven feed members and said weighing means for automatically closing said gate means and deactivating said feed members in response to a preselected weight of powder in said weigh hopper,

. vacuum transfer means for conveying the weighed amount of powder from said weigh hopper to said container, said transfer means including a conduit connected to said weigh hopper and to said container, a vacuum line communicable with said conduit so that the powder can be forced through said conduit into said container, and valve means in said conduit and said vacuum line,

i. liquid supply means connected to said container for introducing a measured volume of liquid into said container, said liquid supply means including a liquid supply pipe, valve means in said pipe operable to open and close said pipe, and means responsive to a predetermined volume of liquid flow in said pipe for closing said valve means,

j. means for placing said container under a vacuum during mixing of the slurry,

k. a chamber in which flasks are filled with slurry, said chamber including an opening and a door for said opening,

1. flask-filling means in said chamber,

in. a vacuum line connected to said chamber and,

n. means including a valve connecting said container to said flask filling means. 7

2. An apparatus as claimed in claim 1 including means for controlling the transfer of powder from said weigh hopper to said container comprising switch means and a timer in electrical circuit relation with said valve means of said vacuum transfer means, said timer being operable to maintain said vacuum transfer valve means in an open position for a predetermined period of time during which powder is transferred to said container and thereafter to cause said vacuum transfer valve means to be closed.

3. An apparatus as claimed in claim 2 including actuator means for moving said door of said chamber between open and closed positions, valving means located in said vacuum line connected to said chamber, means electrically connected to said valving means and operated in response to movement of said door to said closed position for causing said chamber to be placed under a vacuum, flask holding means movable into and out of said chamber through said opening, and means for moving said flask holding means out of said chamber in response to movement of said door to said open position.

4. An investment apparatus comprising:

. a. a container for use in mixing refractory powder and liquid to make an investment slurry,

b. power actuated mixer means in said container,

' c. powder supply means including a feed hopper having a discharge outlet and gate means which is selectively actuatable to open and close said outlet,

d. a power driven feed member associated with said feed hopper for feeding powder through said discharge outlet,

e. weighing means for weighing out a desired amount of powder, said weighing means including a weigh hopper positioned to receive powder discharged from said feed hopper,

f. control means in circuit relation with said gate means, said powder driven feed member and said weighing means for automatically closing said gate means and deactivating said feed member in response to a preselected weight of powder in said weigh hopper,

. vacuum transfer means for conveying the weighed h. liquid supply means connected to said container for introducing a measured amount of liquid into said container, said liquid supply means including a liquid supply pipe, valve means in said pipe operable to open and close said pipe, and means responsive to predetermined volume of liquid flow in said pipe for closing said valve means,

i. means including a vacuum valve connected to said container for placing said container under a vacuum during mixing of the slurry,

j. timer means operatively coupled with said power actuated mixing means, said vacuum valve and said valve means in said conduit and said vacuum line for timing out a predetermined period during which powder is transferred to said container an thereafter controlling the time of mixing of the slurry in said container,

k. a chamber in which flasks are filled with slurry,

said chamber including an opening and a door for said opening, said door being movable between open and closed positions,

1. flask-filling means in said chamber, m. vacuum means connected to said chamber, n. actuator means for moving said door of said chamber between said opened and closed positions, said actuator means being coupled with said timer means to cause said door to be opened at the end of a predetermined time. 

1. An investment apparatus comprising: a. a container for use in mixing refractory powder and liquid to make an investment slurry, b. power actuated mixing means in said container, c. powder supply means including a portable bin and a power driven feed member associated with said bin for assisting in discharging powder therefrom, d. a feed hopper for receiving powder discharged from said portable bin, said feed hopper having a discharge outlet and gate means selectively actuatable to open and close said outlet, e. a power driven feed member associated with said feed hopper for feeding powder through said discharge outlet when it has been opened by said gate means, f. weighing means for weighing out a desired amount of powder, said weighing means including a weigh hopper positioned to receive powder discharged from said feed hopper, g. control means in electrical circuit relation with said gate means, said power driven feed members and said weighing means for automatically closing said gate means and deactivating said feed members in response to a preselected weight of powder in said weigh hopper, h. vacuum transfer means for conveying the weighed amount of powder from said weigh hopper to said container, said transfer means including a conduit connected to said weigh hopper and to said container, a vacuum line communicable with said conduit so that the powder can be forced through said conduit into said container, and valve means in said conduit and said vacuum line, i. liquid supply means connected to said container for introducing a measured volume of liquid into said container, said liquid supply means including a liquid supply pipe, valve means in said pipe operable to open and close said pipe, and means responsive to a predetermined volume of liquid flow in said pipe for closing said valve means, j. means for placing said container under a vacuum during mixing of the slurry, k. a chamber in which flasks are filled with slurry, said chamber including an opening and a door for said opening, l. flask-filling means in said chamber, m. a vacuum line connected to said chamber and, n. means including a valve connecting said container to said flask filling means.
 1. An investment apparatus comprising: a. a container for use in mixing refractory powder and liquid to make an investment slurry, b. power actuated mixing means in said container, c. powder supply means including a portable bin and a power driven feed member associated with said bin for assisting in discharging powder therefrom, d. a feed hopper for receiving powder discharged from said portable bin, said feed hopper having a discharge outlet and gate means selectively actuatable to open and close said outlet, e. a power driven feed member associated with said feed hopper for feeding powder through said discharge outlet when it has been opened by said gate means, f. weighing means for weighing out a desired amount of powder, said weighing means including a weigh hopper positioned to receive powder discharged from said feed hopper, g. control means in electrical circuit relation with said gate means, said power driven feed members and said weighing means for automatically closing said gate means and deactivating said feed members in response to a preselected weight of powder in said weigh hopper, h. vacuum transfer means for conveying the weighed amount of powder from said weigh hopper to said container, said transfer means including a conduit connected to said weigh hopper and to said container, a vacuum line communicable with said conduit so that the powder can be forced through said conduit into said container, and valve means in said conduit and said vacuum line, i. liquid supply means connected to said container for introducing a measured volume of liquid into said container, said liquid supply means including a liquid supply pipe, valve means in said pipe operable to open and close said pipe, and means responsive to a predetermined volume of liquid flow in said pipe for closing said valve means, j. means for placing said container under a vacuum during mixing of the slurry, k. a chamber in which flasks are filled with slurry, said chamber including an opening and a door for said opening, l. flask-filling means in said chamber, m. a vacuum line connected to said chamber and, n. means including a valve connecting said container to said flask filling means.
 2. An apparatus as claimed in claim 1 including means for controlling the transfer of powder from said weigh hopper to said container comprising switch means and a timer in electrical circuit relation with said valve means of said vacuum transfer means, said timer being operable to maintain said vacuum transfer valve means in an open position for a predetermined period of time during which powder is transferred to said container and thereafter to cause said vacuum transfer valve means to be closed.
 3. An apparatus as claimed in claim 2 including actuator means for moving said door of said chamber between open and closed positions, valving means located in said vacuum line connected to said chamber, means electrically connected to said valving means and operated in response to movement of said door to said closed position for causing said chamber to be placed under a vacuum, flask holding means movable into and out of said chamber through said opening, and means for moving said flask holding means out of said chamber in response to movement of said door to said open position. 